Help with quantum physics

1. Mar 30, 2016

JakeP

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >

Hello guys, i need some help in clarifying a question.

A beam of ultraviolet light with wavelength of 200nm is incident on a metal whose work function is 3.0eV. Note that this metal is applied with +1.0V with respect to the ground, Determine the largest kinetic energy of the photoelectrons generated in this process.

Using the formula of KEmax = hf - work function, i can come up with an answer for it. However, from the question, it states the metal is applied with +1.0V with respect to the ground;Does this Voltage affect the KEmax? Because if i were to find stopping potential Vs using E=q|Vs|, Vs will result in approximately 6.211V, taking q to be 1.6 x 10^-19. So i believe that this voltage across the metal is redundant in the calculation.

Thank you guys!

Last edited by a moderator: Mar 30, 2016
2. Mar 30, 2016

Staff: Mentor

So if the applied potential was 6.211 V instead of 1 V, what would you answer for KEmax?

3. Mar 31, 2016

JakeP

Won't it be the same as KEmax?

4. Apr 3, 2016

xTyler

I'm quite confused, is it alright to assume that the applied +1V on the metal is also the stopping voltage? And does this applied voltage on the metal makes it harder for the electrons to break the bond from metal -> Vacuum -> Being ejected ?

5. Apr 6, 2016

Staff: Mentor

No. As said, the stopping potential is 6.211 V.

No. It changes what happens to the freed electron.

6. Apr 6, 2016

Staff: Mentor

What is the definition of the stopping potential?

7. Apr 6, 2016

JakeP

I had this question figured out. Thanks!